Space station

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The modular International Space Station, the largest human-made body in Earth orbit STS-135 final flyaround of ISS 1.jpg
The modular International Space Station, the largest human-made body in Earth orbit

A space station, also known as an orbital station or an orbital space station, is a spacecraft capable of supporting crewmembers, which is designed to remain in space (most commonly as an artificial satellite in low Earth orbit) for an extended period of time and for other spacecraft to dock. A space station is distinguished from other spacecraft used for human spaceflight by lack of major propulsion or landing systems. Instead, other vehicles transport people and cargo to and from the station. As of 2018, one fully functioning space station is in Earth orbit: the International Space Station (operational and permanently inhabited). Various other components of future space stations, such as Japan's space elevator and U.S. inflatable modules, are also being tested in orbit. Previous stations include the Almaz and Salyut series, Skylab, Mir , and Tiangong-1 and Tiangong-2 . China, Russia, the U.S., as well as a few private companies are all planning other stations for the coming decades.

Spacecraft manned vehicle or unmanned machine designed to fly in outer space

A spacecraft is a vehicle or machine designed to fly in outer space. Spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle.

Outer space Void between celestial bodies

Outer space, or just space, is the expanse that exists beyond the Earth and between celestial bodies. Outer space is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature, as set by the background radiation from the Big Bang, is 2.7 kelvins. The plasma between galaxies accounts for about half of the baryonic (ordinary) matter in the universe; it has a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins; local concentrations of this plasma have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces. Observations suggest that the majority of the mass-energy in the observable universe is a poorly understood vacuum energy of space, which astronomers label dark energy. Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space.

Low Earth orbit Orbit around Earth with an altitude between 160 kilometers and 2,000 kilometers

A Low Earth Orbit (LEO) is an Earth-centered orbit with an altitude of 2,000 km (1,200 mi) or less, or with at least 11.25 periods per day and an eccentricity less than 0.25. Most of the manmade objects in space are in LEO. A histogram of the mean motion of the cataloged objects shows that the number of objects drops significantly beyond 11.25.


Today's space stations are research platforms, used to study the effects of long-term space flight on the human body as well as to provide platforms for greater number and length of scientific studies than available on other space vehicles. Each crew member stays aboard the station for weeks or months, but rarely more than a year. Since the ill-fated flight of Soyuz 11 to Salyut 1, all human spaceflight duration records have been set aboard space stations. The duration record for a single spaceflight is 437.7 days, set by Valeriy Polyakov aboard Mir from 1994 to 1995. As of 2016, four cosmonauts have completed single missions of over a year, all aboard Mir. Space stations have also been used for both military and civilian purposes. The last military-use space station was Salyut 5, which was used by the Almaz program of the Soviet Union in 1976 and 1977. [1]

Soyuz 11 Manned Soviet space mission to the Salyut 1 Space Station

Soyuz 11 was the only manned mission to board the world's first space station, Salyut 1. The crew, Georgy Dobrovolsky, Vladislav Volkov, and Viktor Patsayev, arrived at the space station on 7 June 1971 and departed on 29 June. The mission ended in disaster when the crew capsule depressurized during preparations for reentry, killing the three-man crew. The three crew members of Soyuz 11 are the only humans known to have died in space.

Salyut 1 First space station in Earth orbit

Salyut 1 (DOS-1) was the first space station of any kind, launched into low Earth orbit by the Soviet Union on April 19, 1971. The Salyut program followed this with five more successful launches of seven more stations. The final module of the program, Zvezda (DOS-8) became the core of the Russian segment of the International Space Station and remains in orbit.

Salyut 5 Soviet space station launched in 1976

Salyut 5, also known as OPS-3, was a Soviet space station. Launched in 1976 as part of the Salyut programme, it was the third and last Almaz space station to be launched for the Soviet military. Two Soyuz missions visited the station, each manned by two cosmonauts. A third Soyuz mission attempted to visit the station, but failed to dock, whilst a fourth mission was planned but never launched.


Early concepts

Rotating space station envisioned by Herman Potocnik in The Problem of Space Travel (1929) Noordung space station.jpg
Rotating space station envisioned by Herman Potočnik in The Problem of Space Travel (1929)

Space stations have been envisaged since at least as early as 1869 when Edward Everett Hale wrote "The Brick Moon". [2] The first to give serious consideration to space stations were Konstantin Tsiolkovsky in the early 20th century and Hermann Oberth about two decades later. [3] In 1929 Herman Potočnik's The Problem of Space Travel was published, the first to envision a "rotating wheel" space station to create artificial gravity. [2]

Edward Everett Hale American author and Unitarian clergyman

Edward Everett Hale was an American author, historian, and Unitarian minister, best known for his writings such as "The Man Without a Country", published in Atlantic Monthly, in support of the Union during the Civil War. He was the grand-nephew of Nathan Hale, the American spy during the Revolutionary War.

"The Brick Moon" is a novella by American writer Edward Everett Hale, published serially in The Atlantic Monthly starting in 1869. It is a work of speculative fiction containing the first known depiction of an artificial satellite.

Konstantin Tsiolkovsky Russian and Soviet rocket scientist and pioneer of the astronautic theory

Konstantin Eduardovich Tsiolkovsky was a Russian rocket scientist and pioneer of astronautics. Along with the French Robert Esnault-Pelterie, the German Hermann Oberth and the American Robert H. Goddard, he is considered to be one of the founding fathers of modern rocketry and astronautics. His works later inspired leading Soviet rocket engineers such as Sergei Korolev and Valentin Glushko and contributed to the success of the Soviet space program.

During the Second World War, German scientists researched the theoretical concept of an orbital weapon based on a space station. Pursuing Oberth's idea of a space-based weapon, the so-called "sun gun" was a concept of a space station orbiting Earth at a height of 8,200 kilometres (5,100 mi), with a weapon that was to utilize the sun's energy. [4]

Sun gun

The sun gun or heliobeam is a theoretical orbital weapon, which makes use of a concave mirror mounted on a satellite, to concentrate sunlight onto a small area at the Earth's surface, destroying targets or killing through heat.

In 1951, in Collier's Weekly , Wernher von Braun published his design for a rotating wheel space station, which referenced Potočnik's idea – however these concepts would never leave the concept stage during the 20th century. [3]

Wernher von Braun German, later an American, aerospace engineer and space architect

Wernher Magnus Maximilian Freiherr von Braun was a German-American aerospace engineer and space architect. He was the leading figure in the development of rocket technology in Germany and a pioneer of rocket technology and space science in the United States.

Rotating wheel space station

A rotating wheel space station, or von Braun wheel, is a hypothetical wheel-shaped space station that rotates about its axis, thus creating an environment of artificial gravity. Occupants of the station would experience centripetal acceleration according to the following equation,

During the same time as von Braun pursued Potočnik's ideas, the Soviet design bureaus – chiefly Vladimir Chelomey's OKB-52 – were pursuing Tsiolkovsky's ideas for space stations. The work by OKB-52 would lead to the Almaz programme and (together with OKB-1) to the first space station: Salyut 1. The developed hardware laid the ground for the Salyut and Mir space stations, and is even today a considerable part of the ISS space station. [5]

Vladimir Chelomey Soviet aerospace engineer

Vladimir Nikolayevich Chelomey was a Soviet mechanics scientist, aviation and missile engineer. He invented the very first Soviet pulse jet engine and was responsible for the development of the world's first anti-ship cruise missiles and ICBM complexes like the UR-100, UR-200, UR-500 and UR-700.

Salyut programme

The Salyut programme was the first space station programme, undertaken by the Soviet Union. It involved a series of four crewed scientific research space stations and two crewed military reconnaissance space stations over a period of 15 years, from 1971 to 1986. Two other Salyut launches failed. In one respect, Salyut had the task of carrying out long-term research into the problems of living in space and a variety of astronomical, biological and Earth-resources experiments, and on the other hand the USSR used this civilian program as a cover for the highly secretive military Almaz stations, which flew under the Salyut designation. Salyut 1, the first station in the program, became the world's first crewed space station.

International Space Station Habitable artificial satellite in low Earth orbit

The International Space Station (ISS) is a space station, or a habitable artificial satellite, in low Earth orbit. Its first component was launched into orbit in 1998, with the first long-term residents arriving in November 2000. It has been inhabited continuously since that date. The last pressurised module was fitted in 2011, and an experimental inflatable space habitat was added in 2016. The station is expected to operate until 2030. Development and assembly of the station continues, with several new elements scheduled for launch in 2019. The ISS is the largest human-made body in low Earth orbit and can often be seen with the naked eye from Earth. The ISS consists of pressurised habitation modules, structural trusses, solar arrays, radiators, docking ports, experiment bays and robotic arms. ISS components have been launched by Russian Proton and Soyuz rockets and American Space Shuttles.

Salyut, Almaz, and Skylab (1971–1986)

The U.S. Skylab station of the 1970s Skylab 3 flyaround.jpg
The U.S. Skylab station of the 1970s

The first space station was Salyut 1, which was launched by the Soviet Union on April 19, 1971. Like all the early space stations, it was "monolithic", intended to be constructed and launched in one piece, and then inhabited by a crew later. As such, monolithic stations generally contained all their supplies and experimental equipment when launched, and were considered "expended", and then abandoned, when these were used up. [5]

The earlier Soviet stations were all designated "Salyut", but among these there were two distinct types: civilian and military. The military stations, Salyut 2, Salyut 3, and Salyut 5, were also known as Almaz stations. [6]

The civilian stations Salyut 6 and Salyut 7 were built with two docking ports, which allowed a second crew to visit, bringing a new spacecraft with them; the Soyuz ferry could spend 90 days in space, after which point it needed to be replaced by a fresh Soyuz spacecraft. [7] This allowed for a crew to man the station continually. Skylab was also equipped with two docking ports, like second-generation stations, but the extra port was never utilized. The presence of a second port on the new stations allowed Progress supply vehicles to be docked to the station, meaning that fresh supplies could be brought to aid long-duration missions. This concept was expanded on Salyut 7, which "hard docked" with a TKS tug shortly before it was abandoned; this served as a proof-of-concept for the use of modular space stations. The later Salyuts may reasonably be seen as a transition between the two groups. [6]

Mir (1986–2001)

Earth and the Mir station Mir during STS-74 (cropped).jpg
Earth and the Mir station

Unlike previous stations, the Soviet space station Mir had a modular design; a core unit was launched, and additional modules, generally with a specific role, were later added to that. This method allows for greater flexibility in operation, as well as removing the need for a single immensely powerful launch vehicle. Modular stations are also designed from the outset to have their supplies provided by logistical support, which allows for a longer lifetime at the cost of requiring regular support launches. [8]

Future modules are still based on initial design and capabilities.

ISS (1998–present)

ISS under construction STS-116 spacewalk 1.jpg
ISS under construction

The first module of the International Space Station, Zarya, was launched in 1998. [9] The ISS is divided into two main sections, the Russian Orbital Segment (ROS) and the US Orbital Segment (USOS).

USOS modules were brought to the station by the Space Shuttle and manually attached to the ISS by crews during EVAs. Connections are made manually for electrical power, data, propulsion and cooling fluids. This results in a single piece which is not designed for disassembly. [10]

The Russian Orbital Segment's modules are able to launch, fly and dock themselves without human intervention using Proton rockets. [11] Connections are automatically made for power, data and propulsion fluids and gases. The Russian approach would hypothetically allow the assembly of space stations orbiting other worlds in preparation for human missions.

Russian modular or "second-generation" space stations differ from "monolithic" single-piece stations by allowing reconfiguration of the station to suit changing needs. According to a 2009 report, RKK Energia considered removing some modules of the ROS when the end of mission is reached for the ISS to reuse them as parts of a new station, known as the Orbital Piloted Assembly and Experiment Complex. [12] However, in September 2017 the head of Roscosmos said that the technical feasibility of separating the station to form OPSEK had been studied, and there were now no plans to separate the Russian segment from the ISS. [13]

Tiangong program (2011–present)

China's first space laboratory, Tiangong-1 was launched in September 2011. [14] The uncrewed Shenzhou 8 then successfully performed an automatic rendezvous and docking in November 2011. The crewed Shenzhou 9 then docked with Tiangong-1 in June 2012, the crewed Shenzhou 10 in 2013. A second space laboratory Tiangong-2 was launched in September 2016, while a plan for Tiangong-3 was merged with Tiangong-2. [15]

In May 2017, China informed the United Nations Office for Outer Space Affairs that Tiangong-1's altitude was decaying and that it would soon reenter the atmosphere and break up. [15] The reentry was projected to occur in late March or early April 2018. [16] According to the China Manned Space Engineering Office, Tiangong-1 reentered over the South Pacific Ocean, northwest of Tahiti, on 2 April 2018 at 00:15 UTC. [17] [18] [19] [20] [21]


Astronauts peer out of Destiny Laboratory, 2001 Sts100-Destiny.jpg
Astronauts peer out of Destiny Laboratory, 2001
Solar arrays of space station modules backlit by the Sun ROSSA.jpg
Solar arrays of space station modules backlit by the Sun

The space station environment presents a variety of challenges to human habitability, including short-term problems such as the limited supplies of air, water and food and the need to manage waste heat, and long-term ones such as weightlessness and relatively high levels of ionizing radiation. These conditions can create long-term health problems for space-station inhabitants, including muscle atrophy, bone deterioration, balance disorders, eyesight disorders, and elevated risk of cancer. [22]

Future space habitats may attempt to address these issues, and could be designed for occupation beyond the weeks or months that current missions typically last. Possible solutions include the creation of artificial gravity by a rotating structure, the inclusion of radiation shielding, and the development of on-site agricultural ecosystems. Some designs might even accommodate large numbers of people, becoming essentially "cities in space" where people would reside semi-permanently. For now, no space station suitable for long-term human residence has ever been built, since the current launch costs for even a small station are not economically or politically viable. [23]


A space station is a complex system with many interrelated subsystems, including structure, electrical power, thermal control, attitude determination and control, orbital navigation and propulsion, automation and robotics, computing and communications, environmental and life support, crew facilities, and crew and cargo transportation.

Environmental microbiology

Despite an expanding array of molecular approaches for detecting microorganisms, rapid and robust means of assessing the differential viability of the microbial cells, as a function of phylogenetic lineage, remain elusive. Molds that develop aboard space stations can produce acids that degrade metal, glass and rubber. [24]

List of space stations

The Soviet space stations came in two types, the civilian Durable Orbital Station (DOS), and the military Almaz stations.
Dates refer to periods when stations were inhabited by crews.

Tiangong 2Tiangong 1Genesis IIGenesis IInternational Space StationMirSalyut 7Salyut 6Salyut 5Salyut 4Salyut 3SkylabKosmos 557Salyut 2DOS-2Salyut 1OPS 0855Space station

Canceled projects

1967 conceptual drawing of Gemini B reentry module separating from the Manned Orbital Laboratory (MOL) (USAF) MOL USAF.png
1967 conceptual drawing of Gemini B reentry module separating from the Manned Orbital Laboratory (MOL) (USAF)

Planned projects

Interior view of an O'Neill cylinder Spacecolony3edit.jpeg
Interior view of an O'Neill cylinder
Proposed Exploration Gateway Platform at EML-1 ExplorationGatewayPlatform components.jpg
Proposed Exploration Gateway Platform at EML-1

See also

Related Research Articles

<i>Mir</i> Soviet/Russian space station that operated in Earth orbit from 1986 to 2001

Mir was a space station that operated in low Earth orbit from 1986 to 2001, operated by the Soviet Union and later by Russia. Mir was the first modular space station and was assembled in orbit from 1986 to 1996. It had a greater mass than any previous spacecraft. At the time it was the largest artificial satellite in orbit, succeeded by the International Space Station (ISS) after Mir's orbit decayed. The station served as a microgravity research laboratory in which crews conducted experiments in biology, human biology, physics, astronomy, meteorology and spacecraft systems with a goal of developing technologies required for permanent occupation of space.

Salyut 2 Soviet space station which was launched in 1973

Salyut 2 (OPS-1) was a Soviet space station which was launched in 1973 as part of the Salyut programme. It was the first Almaz military space station to fly. Within two weeks of its launch, the station had lost attitude control and depressurised, leaving it unusable. Its orbit decayed and it re-entered the atmosphere on 28 May 1973, without any crews having visited it.

Salyut 7 space station launched on 19 April 1982

Salyut 7 was a space station in low Earth orbit from April 1982 to February 1991. It was first manned in May 1982 with two crew via Soyuz T-5, and last visited in June 1986, by Soyuz T-15. Various crew and modules were used over its lifetime, including 12 manned and 15 unmanned launches in total. Supporting spacecraft included the Soyuz T, Progress, and TKS spacecraft.

Almaz Soviet military space station program

The Almaz program was a highly secret Soviet military space station program, begun in the early 1960s.

TKS (spacecraft) Soviet spacecraft conceived in the late 1960s

The TKS spacecraft was a Soviet spacecraft conceived in the late 1960s for resupply flights to the military Almaz space station.

Shuttle–<i>Mir</i> Program Space program between Russia and the United States

The Shuttle–Mir Program was a collaborative space program between Russia and the United States, which involved American Space Shuttles visiting the Russian space station Mir, Russian cosmonauts flying on the shuttle, and an American astronaut flying aboard a Soyuz spacecraft to engage in long-duration expeditions aboard Mir.

VA spacecraft

The Vozvraschaemyi Apparat, or VA spacecraft, was a Soviet crew capsule, intended to serve as a manned launch and reentry vehicle. Initially designed for the LK-1 manned lunar flyby spacecraft for one of the Soviet manned lunar programs, then the LK-700 redesign, it was later repurposed for the Almaz military space station program. The VA capsule on display at the Smithsonian National Air and Space Museum was labeled as Merkur, following a mistranslation of the original documentation – while incorrect, the name is being used in the West for the VA spacecraft and capsule.

Chinese large modular space station planned space station to be placed in Low Earth orbit

The Chinese large modular space station is a planned space station to be placed in Low Earth orbit. The planned Chinese Space Station will be roughly one-fifth the mass of the International Space Station and about the size of the decommissioned Russian Mir space station. The Chinese station is expected to have a mass between 80 to 100 metric tons. Operations will be controlled from the Beijing Aerospace Command and Control Center in China. The planned launch date of the core module, the Tianhe-1, is 2020. In 2017, the Chinese launched the Tianzhou-1 cargo spaceship, which is based on the Tiangong 1 & 2 space laboratories.

History of spaceflight aspect of history

Spaceflight began in the 20th century following theoretical and practical breakthroughs by Konstantin Tsiolkovsky and Robert H. Goddard. The Soviet Union took the lead in the post-war Space Race, launching the first satellite, the first man and the first woman into orbit. The United States caught up with, and then passed, their Soviet rivals during the mid-1960s, landing the first man on the Moon in 1969. In the same period, France, the United Kingdom, Japan and China were concurrently developing more limited launch capabilities.

Kosmos 1686

Kosmos 1686, also known as TKS-4, was a heavily modified TKS spacecraft which docked unmanned to the Soviet space station Salyut 7 as part of tests to attach scientific expansion modules to stations in Earth orbit. The module which docked to the station was the FGB component of a TKS vehicle launched on September 27, 1985, and was designed to test systems planned for use on the Mir Core Module. The spacecraft docked with Salyut 7 on October 2, 1985, during the long-duration stay of the cosmonauts of its fifth principal expedition, which arrived on Soyuz T-14. It was the last flown TKS spacecraft.

Russian Orbital Segment Russian components of the International Space Station

The Russian Orbital Segment (ROS) is the name given to the components of the International Space Station (ISS) constructed in Russia and operated by the Russian Federal Space Agency (Roscosmos). The ROS handles Guidance, Navigation & Control for the entire Station.

Orbital Piloted Assembly and Experiment Complex

The Orbital Piloted Assembly and Experiment Complex was a 2009–2017 Russian proposed third-generation modular space station for Low Earth orbit.

Docking and berthing of spacecraft joining of two or more space vehicles

Docking and berthing of spacecraft is the joining of two space vehicles. This connection can be temporary, or semipermanent such as for space station modules.

Core Cabin Module Component of Chinas space station

The Tianhe, code name TH, or Core Cabin Module (CCM) is the foundation element of the Chinese space station, as the final stage of Project 921 Tiangong program, part of the Chinese space program. The CCM follows the Salyut and Almaz series, Cosmos 557, Skylab, Mir, ISS, Tiangong 1 and Tiangong 2 space stations. It is the first part of a third generation modular space station. Other examples of modular station projects include the Soviet/Russian Mir, Russian OPSEK, and the International Space Station. Operations will be controlled from the Beijing Aerospace Command and Control Center in the People's Republic of China. In 2018 fullscale mockup of CCM was publicly presented at China International Aviation & Aerospace Exhibition in Zhuhai


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